Vα24 NKT Cells: Ex Vivo Expansion, Specificity, And Function

NKT cells bridge the innate and adaptive immune systems. When triggered by lipid or glycolipid-antigens, they could produce large amounts of cytokines and up-regulate cytotoxic molecules, and may play crucial roles in anti-tumor immunity and transplantation tolerance induction. Human NKT cells, defined as Vα24 NKT cells, express a highly limited T cell receptor (TCR) repertoire which composed of an invariant Vα24 JaQ a-chain and a P-chain biased towards Vβ11. Here we studied to optimize a method for expanding Vα24 NKT cells ex vivo and searched about the effect of specific antigen or varies of cytokines on the expansion. Then we determined the properties of expanded NKT cells and investigated how to promote Thl or Th2 differentiation of NKT cells with different cytokine cocktails. Meanwhile, we evaluated the anti-tumor activity of NKT cells and their inhibitory effect on allogeneic T cell response. Furthermore, the role of human Vα24 NKT cells in human-mouse xenogeneic transplantation was briefly explored in this study.Mononuclear cells (MNCs) isolated from adult peripheral blood or umbilical cord blood (UCB) were divided into three groups, and were cultured with α-galactosylceramide (a-GalCer), interleukin (IL)-2, and IL-15. In Group A1 (n=6) or Group A2 (n=6), cord blood CD34⁺ progenitor- or adult peripheral monocyte-derived dendritic cells acted as antigen presenting cells (APC) to induce the expansion of cord blood or adult peripheral Vα24 NKT cells, respectively; whereas in Group B (n=22), a-GalCer was added into adult peripheral MNCs culture system without additional DCs. During 12-d culture, Vα24 NKT cells from Group A1, A2, and B expanded up to 221.5(95-501), 339(168-1263), and 413.5(101²207)-fold by day 12, respectively. NKT cells from Group B expanded well than those from Group Al (P=0.020). The difference between Group B and A2 (P=0.576) or Group Al and A2 (P=0.132) had no statistical significance. Within the 16 cases had a 2^nd stimulating with a-GalCer, 7 expanded up to 722-28301-fold by d20 and others suffered death. 2 of 7 cases that had...